Publications by authors named "H Charles J Godfray"

188 Publications

Modelling the global economic consequences of a major African swine fever outbreak in China.

Nat Food 2020 Apr 17;1(4):221-228. Epub 2020 Apr 17.

Oxford Martin School & Department of Zoology, University of Oxford, Oxford, UK.

African swine fever is a deadly porcine disease that has spread into East Asia where it is having a detrimental effect on pork production. However, the implications of African swine fever on the global pork market are poorly explored. Two linked global economic models are used to explore the consequences of different scales of the epidemic on pork prices and on the prices of other food types and animal feeds. The models project global pork prices increasing by 17-85% and unmet demand driving price increases of other meats. This price rise reduces the quantity of pork demanded but also spurs production in other parts of the world, and imports make up half the Chinese losses. Demand for, and prices of, food types such as beef and poultry rise, while prices for maize and soybean used in feed decline. There is a slight decline in average per capita calorie availability in China, indicating the importance of assuring the dietary needs of low-income populations. Outside China, projections for calorie availability are mixed, reflecting the direct and indirect effects of the African swine fever epidemic on food and feed markets.
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http://dx.doi.org/10.1038/s43016-020-0057-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7116817PMC
April 2020

Intraspecific variation in symbiont density in an insect-microbe symbiosis.

Mol Ecol 2021 03 11;30(6):1559-1569. Epub 2021 Feb 11.

Department of Zoology, University of Oxford, Oxford, UK.

Many insects host vertically transmitted microbes, which can confer benefits to their hosts but are costly to maintain and regulate. A key feature of these symbioses is variation: for example, symbiont density can vary among host and symbiont genotypes. However, the evolutionary forces maintaining this variation remain unclear. We studied variation in symbiont density using the pea aphid (Acyrthosiphon pisum) and the bacterium Regiella insecticola, a symbiont that can protect its host against fungal pathogens. We found that relative symbiont density varies both between two Regiella phylogenetic clades and among aphid "biotypes." Higher density symbiont infections are correlated with stronger survival costs, but variation in density has little effect on the protection Regiella provides against fungi. Instead, we found that in some aphid genotypes, a dramatic decline in symbiont density precedes the loss of a symbiont infection. Together, our data suggest that the optimal density of a symbiont infection is likely different from the perspective of aphid and microbial fitness. Regiella might prevent loss by maintaining high within-host densities, but hosts do not appear to benefit from higher symbiont numbers and may be advantaged by losing costly symbionts in certain environments. The standing variation in symbiont density observed in natural populations could therefore be maintained by antagonistic coevolutionary interactions between hosts and their symbiotic microbes.
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http://dx.doi.org/10.1111/mec.15821DOI Listing
March 2021

80 questions for UK biological security.

PLoS One 2021 6;16(1):e0241190. Epub 2021 Jan 6.

Centre for Pathogen Evolution, Department of Zoology, University of Cambridge, Cambridge, United Kingdom.

Multiple national and international trends and drivers are radically changing what biological security means for the United Kingdom (UK). New technologies present novel opportunities and challenges, and globalisation has created new pathways and increased the speed, volume and routes by which organisms can spread. The UK Biological Security Strategy (2018) acknowledges the importance of research on biological security in the UK. Given the breadth of potential research, a targeted agenda identifying the questions most critical to effective and coordinated progress in different disciplines of biological security is required. We used expert elicitation to generate 80 policy-relevant research questions considered by participants to have the greatest impact on UK biological security. Drawing on a collaboratively-developed set of 450 questions, proposed by 41 experts from academia, industry and the UK government (consulting 168 additional experts) we subdivided the final 80 questions into six categories: bioengineering; communication and behaviour; disease threats (including pandemics); governance and policy; invasive alien species; and securing biological materials and securing against misuse. Initially, the questions were ranked through a voting process and then reduced and refined to 80 during a one-day workshop with 35 participants from a variety of disciplines. Consistently emerging themes included: the nature of current and potential biological security threats, the efficacy of existing management actions, and the most appropriate future options. The resulting questions offer a research agenda for biological security in the UK that can assist the targeting of research resources and inform the implementation of the UK Biological Security Strategy. These questions include research that could aid with the mitigation of Covid-19, and preparation for the next pandemic. We hope that our structured and rigorous approach to creating a biological security research agenda will be replicated in other countries and regions. The world, not just the UK, is in need of a thoughtful approach to directing biological security research to tackle the emerging issues.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0241190PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7787535PMC
January 2021

Modelling the suppression of a malaria vector using a CRISPR-Cas9 gene drive to reduce female fertility.

BMC Biol 2020 08 11;18(1):98. Epub 2020 Aug 11.

Oxford Martin School, University of Oxford, Oxford, UK.

Background: Gene drives based on CRISPR-Cas9 technology are increasingly being considered as tools for reducing the capacity of mosquito populations to transmit malaria, and one of the most promising options is driving endonuclease genes that reduce the fertility of female mosquitoes. In particular, there is much interest in constructs that target the conserved mosquito doublesex (dsx) gene such that the emergence of functional drive-resistant alleles is unlikely. Proof of principle that these constructs can lead to substantial population suppression has been obtained in population cages, and they are being evaluated for use in sub-Saharan Africa. Here, we use simulation modelling to understand the factors affecting the spread of this type of gene drive over a one million-square kilometre area of West Africa containing substantial environmental and social heterogeneity.

Results: We found that a driving endonuclease gene targeting female fertility could lead to substantial reductions in malaria vector populations on a regional scale. The exact level of suppression is influenced by additional fitness costs of the transgene such as the somatic expression of Cas9, and its deposition in sperm or eggs leading to damage to the zygote. In the absence of these costs, or of emergent drive-resistant alleles that restore female fertility, population suppression across the study area is predicted to stabilise at ~ 95% 4 years after releases commence. Small additional fitness costs do not greatly affect levels of suppression, though if the fertility of females whose offspring transmit the construct drops by more than ~ 40%, then population suppression is much less efficient. We show the suppression potential of a drive allele with high fitness costs can be enhanced by engineering it also to express male bias in the progeny of transgenic males. Irrespective of the strength of the drive allele, the spatial model predicts somewhat less suppression than equivalent non-spatial models, in particular in highly seasonal regions where dry season stochasticity reduces drive efficiency. We explored the robustness of these results to uncertainties in mosquito ecology, in particular their method of surviving the dry season and their dispersal rates.

Conclusions: The modelling presented here indicates that considerable suppression of vector populations can be achieved within a few years of using a female sterility gene drive, though the impact is likely to be heterogeneous in space and time.
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http://dx.doi.org/10.1186/s12915-020-00834-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7422583PMC
August 2020

Multiple phenotypes conferred by a single insect symbiont are independent.

Proc Biol Sci 2020 06 17;287(1929):20200562. Epub 2020 Jun 17.

Department of Zoology, University of Oxford, 11a Mansfield Road, Oxford, OX1 3SZ, UK.

Many microbial symbionts have multiple phenotypic consequences for their animal hosts. However, the ways in which different symbiont-mediated phenotypes combine to affect fitness are not well understood. We investigated whether there are correlations between different symbiont-mediated phenotypes. We used the symbiont , a striking example of a bacterial symbiont conferring diverse phenotypes on insect hosts. We took 11 strains of infecting pea aphids () and assessed their ability to provide protection against the fungal pathogen and the parasitoids and . We also assessed effects on male offspring production for five of the strains. All but one of the strains provided very strong protection against the parasitoid . As previously reported, variable protection against and was also present; male-killing was likewise a variable phenotype. We find no evidence of any correlation, positive or negative, between the different phenotypes, nor was there any evidence of an effect of symbiont phylogeny on protective phenotype. We conclude that multiple symbiont-mediated phenotypes can evolve independently from one another without trade-offs between them.
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http://dx.doi.org/10.1098/rspb.2020.0562DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7329050PMC
June 2020